docs: def get_html_tag_attributes(cls, instance):
          """
          Returns a dictionary of attributes, which shall be added to the current HTML tag.
          This method normally is called by the models's property method ``html_tag_ attributes``,
          which enriches the HTML tag with those attributes converted to a list as
          ``attr1="val1" attr2="val2" ...``.
          """
          attributes = getattr(cls, 'html_tag_attributes', {})
          return dict((attr, instance.glossary.get(key, '')) for key, attr in attributes.items())